Mothocya rosea Bruce, 1986

This is the first record for this species in San Francisco Bay.  It was collected from a trawl sample near Dumbarton Point. The type locality for this species is Baja California.

Cymothid isopods are all parasites of fish, and are well adapted to the parasitic lifestyle, with prehensile, grasping legs and mouthparts with stout, curved spine-like setae that help the animal hold on to and transfer blood from the host fish.

All cymothids appear to be protandric hermaphrodites, starting life as males, then later transforming into females (unless retained in the male stage by a female already attached to a fish host). Like other isopods, the young are brooded in a special pouch or marsupium formed from modified abdominal appendages.

Cymotha rosea is host-specific to the California halfbeak Hyporhamphus rosea. The northernmost record for this species to this point is San Pedro in Los Angeles County. This find represents a new record for San Francisco Bay, as well as a range extension.

Photos by Vic Smith